Work conducted at the Bureau of Mineral Resources (now Geoscience Australia) in the early 1990s was instrumental in bringing Hot Rocks geothermal research and development to Australia. Following the announcement of the Federal Government's Energy Initiative in August 2006, a new geothermal project has been started at Geoscience Australia. Pre-competitive geoscience previously made available for the minerals and petroleum industries has been extremely useful in assisting the geothermal exploration industry to date. This paper outlines the scope of Geoscience Australia's Onshore Energy Security Program and the development, implementation and progress to date of the new Geothermal Energy Project, including new data acquisition programs specifically aimed at assisting geothermal explorers. Geoscience Australia is the Australian government's geoscience and geospatial information agency within the Department of Resources, Energy and Tourism.

Australia's hot rock and hydrothermal resources have the potential to fuel competitively-priced, emission free, renewable baseload power for centuries to come. This potential and the risks posed by climate change are stimulating geothermal energy exploration projects in Australia. Extracting just 1 percent of the estimated energy from rocks hotter than 150°C and shallower than 5,000m would yield ~190 million PJ or about 26,000 times Australia's primary power usage in 2005. This figure does not take into account the renewable characteristics of hot rock, nor the resource below 5,000m. To year-end 2007, thirty-three companies have joined the hunt for geothermal energy resources in 277 licence application areas covering more than 219,000 km2 in Australia. Companies are targeting resources that fall into two categories: (1) hydrothermal resources in relatively hot sedimentary basins; and (2) hot rocks. Most exploration efforts are currently focused on hot rocks to develop Enhanced Geothermal Systems (EGS) to fuel binary power plants. Roughly 80 percent of these projects are located in South Australia. The basic geologic factors that limit the extent of hot rock plays can be generalised as: - source rocks in the form of radiogenic, high heat-flow basement rocks; - traps defined by favourable juxtaposition of low (thermal) conductivity insulating rocks to radiogenic heat producing basement rocks; - heat-exchange reservoirs under favourable stress conditions within insulating and basement rocks; and - a practical depth-range limited by drilling and completion technologies (defining a base) and necessary heat exchange efficiency (defining a top). A considerable investment (US$200+ million) is required to prove a sustainable hot rock play, and demonstrate the reliability, scalability and efficiency of EGS power production. The proof-of-concept phase entails the drilling of at least two deep (>3,500m) hot holes (one producer and one injector), fracture stimulation, geofluid flow and reinjection and heat exchange for power generation. Compelling demonstration projects will entail up-scaling, including smooth operations while drilling and completing additional Hot Rock production and injection wells and sustained power production, most probably from binary geothermal power plants. Australian government grants have focused on reducing critical, sector-wide uncertainties and equate to roughly 25% of the cost of the private sector's field efforts to date. A national hot rock resource assessment and a road-map for the commercialisation of Australian hot rock plays will be published in 2008 by the Australia federal government. Play and portfolio assessment methods currently used to manage the uncertainties in petroleum exploration can usefully be adapted to underpin decision-making by companies and governments seeking to respectively push and pull hot rock energy supplies into markets. This paper describes the geology, challenges, investment risk assessment and promising future for hot rock geothermal energy projects in Australia.

The Federal Government has recently committed $58.9M in the Energy Security Initiative between mid 2006 to mid 2011 to identify potential on-shore energy sources such as petroleum and geothermal energy. Using the latest geophysical imaging and mapping techniques, this information will help attract companies to explore in new areas by enhancing the chances of discovery and reducing the risks to investors. The Onshore Energy Security Program includes the acquisition of new seismic, radiometric, magneto-telluric, gravity, magnetic, geochemical and drillhole data in support of exploration for onshore petroleum, uranium and thorium energy sources, in addition to an emphasis on geothermal. Maps of crustal temperature (e.g. Chopra & Holgate, 2005, Proceeding of the World Geothermal Congress, Turkey. www.wgc2005.org) show that the geothermal energy resource in Australia is vast. Electricity is expected to be generated from hydrothermal and hot fractured rock plays, while lower-temperature hydrothermal resources close to population or industry centres may be useable by direct means. The new Geothermal Energy Project in the Onshore Energy and Minerals Division at Geoscience Australia will provide precompetitive geoscience information for geothermal explorers. The two major activities directly in support of geothermal energy exploration are enhanced maps of heat distribution across Australia, and a geothermal information system. Heat distribution throughout Australia will be mapped in three ways: (1) new heat flow measurements in existing and new drillholes; (2) a granite source-sediment heat trap map to identify hot fractured rock systems; and (3) enhancements to the 5km temperature map method of Chopra and Holgate (op cit.). The geothermal information system will include thermal conductivity, thermal gradient, density, and heat production amongst other data types.

The Federal Government has recently committed $58.9M in the Energy Initiative, a four year program scheduled to mid 2011, with the aim of identifying potential new energy sources in Australia. The program is targeted towards a specific range of energy commodities that include onshore geothermal energy. Using the latest geophysical imaging and mapping techniques, Geoscience Australia (GA) aims to provide pre-competitive geoscientific information that will help attract companies to explore in new areas by enhancing the chances of discovery and reducing the risks to investors. GA's Onshore Energy Security Program includes the acquisition of new seismic, radiometric, magneto-telluric, gravity, magnetic, geochemical and drillhole data in support of exploration for energy sources including geothermal, petroleum, uranium and thorium. Available maps of crustal temperature (Figure 1) clearly illustrate that the geothermal energy resource in Australia is vast. Electricity is expected to be generated from both hydrothermal (hot groundwater in situ e.g. the Great Artesian Basin) and hot fractured rock plays (e.g. buried hot granites within the Cooper Basin). Significant potential also exists for lower-temperature hydrothermal resources close to population or industry centres which may be useable by direct means. Currently the only geothermal energy being used in Australia is that which emanates from a 120kW plant located at Birdsville (Qld) which draws from the relative shallow hot waters of the Great Artesian Basin. The Geothermal Energy Project in the Onshore Energy and Minerals Division at GA aims to support ongoing geothermal energy exploration across Australia via the provision of enhanced maps of heat distribution together with a comprehensive national geothermal information system. Heat distribution throughout Australia will be mapped in three ways: (1) new heat flow measurements in existing and new drillholes; (2) a granite source/sediment heat trap map to identify hot fractured rock systems and potential geothermal plays (Figure 2); and (3) enhancements to the 5km temperature map of Chopra and Holgate (2005; Figure 1). The geothermal information system will comprise a wide range of information including (but not limited to) thermal conductivity, thermal gradient, density, and heat production data.

The hot rock geothermal model in the Australian context comprises high-heat producing granites overlain by thick accumulations of low-thermal conductivity sediments. The granites have low concentrations of radiogenic elements, and over hundreds of millions of years, these elements decay and produce heat. The passage of this heat to the Earth's surface via upwards conduction is slowed by layers of sediments that have low thermal conductivity, creating "hot spots" beneath the blankets. This thematic map shows granites attributed by heat production and basin depth. The majority of the granites depicted are of surface outcrop. The presence of high-heat producing granites adjacent to deep sedimentary basins may be used as a first-order indicator of where to further investigate the possibility of hot rock geothermal plays. The main frame of the map shows all granites (attributed by calculated heat production where available), sedimentary basins and their order (e.g. where one basin is overlapped by another) and geothermal licenses and applications. The top right inset map shows only those granites with a calculated radiogenic heat generation of >5 Wm-3, and the depths of the sedimentary basins. This map provides a rapid view of areas that may be expected to have the greatest hot rock potential. The second-from-top inset map shows all suitable geochemical analyses from OZCHEM, attributed by calculated radiogenic heat generation. This shows both the distribution of data that goes into attributing the granite polygons, and also analyses of granites (and other rocks) that fall outside the mapped granite polygons and are otherwise excluded from the main map. The third-from-top inset map shows the distribution of drillholes that have temperature measurements. The bottom inset map shows an image of the Austherm07 database, which is derived from the drillhole temperature information. The image shows the projected temperature of the crust at a depth of 5km, interpolated between the drillholes. Overlain on this image is the small number of publicly-available heat flow data. This map is GA GeoCat record 65306. ISBN (print): 978-1-921236-44-0; ISBN (web): 978-1-921236-45-7. Webpage: http://www.ga.gov.au/minerals/research/national/geothermal/index.jsp.

Poster describing synthetic thermal modelling and its application to geothermal exploration in Australia

Geothermal energy has received increasing attention over the last decade as a potentially abundant, large scale, cost competitive, base load, safe and low-emission energy source for electricity generation and industrial applications in Australia. Geothermal resources comprise a volume of rock of suitable temperature and permeability, and a heat-transport fluid. High crustal temperatures in Australia are thought to be generated by high heat producing granites being overlain by thermally insulating sediments. Two types of geothermal plays exist in Australia: Hot Rocks, which require reservoir enhancement and possibly the addition of water; and Hot Sedimentary Aquifers in shallow (<3,500 m), permeable, water-saturated sediments. Ground selection by early geothermal explorers in Australia was made based on direct temperature measurements from deep (up to 5 km) petroleum wells. In areas without previous deep drilling, the most robust measurement for predicting temperature at depth for Hot Rock geothermal resources is heat flow, but there are only ~150 publicly-available measurements continent-wide. Targeting for Hot Rock geothermal resources is increasingly being done using other geological datasets acquired for minerals exploration. These datasets include geological maps (lithology, stress, structure), seismic, geochemistry, gravity radiometrics and magnetics. Heat flow measurements are used in petroleum studies and can be of use in exploration for some types of mineral deposits.

The Geoscience Australia Rock Properties database stores the result measurements of scalar and vector petrophysical properties of rock and regolith specimens and hydrogeological data. Oracle database and Open Geospatial Consortium (OGC) web services. Links to Samples, Field Sites, Boreholes. <b>Value:</b> Essential for relating geophysical measurements to geology and hydrogeology and thereby constraining geological, geophysical and groundwater models of the Earth <b>Scope:</b> Data are sourced from all states and territories of Australia

This is a paper submitted for the 29th NZ Geothermal Workshop, presenting information about the geothermal industy in Australia, the impediements the industry faces and Geoscience Australia's role in reducing the geoscience-related impediments. Paper abstract is as follows: Australia's emergent geothermal energy industry is growing rapidly, with 29 geothermal companies currently prospecting for Hot Rock and hydrothermal resources. The Hot Rock model in the Australian context comprises a thick sequence (>3km) of low-thermal conductivity sediments overlying deeper high-heat-producing granites. Until now, the key datasets available to industry to guide their geothermal exploration have been a map of crustal temperature at 5km depth, and heat-flow data. Both datasets suffer from regions of low data density and heterogeneous data distribution. The Australian Government has provided Geoscience Australia with funding for an Onshore Energy Security Program (OESP). Established as part of the OESP, a new Geothermal Project will generate precompetitive geoscientific information for geothermal explorers through two major activities: mapping heat across Australia, and developing a geothermal information system. The Australian Government has also awarded several renewable energy and start-up grants to the geothermal industry since 2000, and is currently funding the preparation of a Geothermal Industry Development Framework (GIDF). The GIDF aims to support the industry by developing strategies to ensure that technical, economic and regulatory obstacles are tackled in a coordinated way.

An extension of previously developed methods to calculate in-situ 3D temperature directly from 3D geology models in 3D GeoModeller software now allows for quantification of the uncertainty associated with those calculations. This work is being collaboratively undertaken by Intrepid Geophysics and Geoscience Australia, and will offer Australia's geothermal industry both: i) a new predictive tool helping to reduce the risk of Enhanced Geothermal System (EGS) exploration and heat resource estimation, and ii) stochastic temperature and heat flow maps of Australia.